Mechanical lead pencil



March 4, 1952 K. J. svENssoN MECHANICAL LEAD PENCIL Filed Sept. 22, 1949Qn. m

A Wx N Patented Mar. 4, 1952 MECHANICAL LEAD PEN CIL Karl. JosefSvensson, Sundbyberg, Sweden Application September 22, 1949, Serial No.117,209 In Sweden November 8, 1948 1 Claim. 1

The present invention relates to a mechanical lead pencil of the type inwhich feeding and retracting of the lead is eiiected by the movement ofa lead holding sleeve having a guide member r pin thereon relative to anouter sleeve surrounding the same and which outer sleeve has alongitudinal slot through which the pin passes to engage in a helicoidalgroove provided on the inner Wall of the casing of the pencil, feedingof .the lead being effected by rotation of a pencil tip which iS securedto the outer sleeve.

More particularly the invention relates to the provision of a safetydevice in a pencil oi this character and which safety device permits thepin to become free of the groove at either end thereof so asto avoiddamage to the pencil upon excess rotation of the tip in eitherdirection.

The invention speciiically relates to the provision of a lead pencilwith a safety means as above indicated in which the tip islongitudinally movable relative to the adjacent end of the casing topermit the pin to rotate free of the groove at the front end of thepencil and a movable abutment means is disposed at the opposite end ofthe groove and normally closes the same butV is movable upon excessrotation of the tip to permit the pin to rotate free of the groove atthe inner end of the same.

In pencils of this type it is known to provide safety means in the formof a plate or ring at each end of the groove in the casing and whichplate or ring is pressed againstJ the end of the casing by a springdisposed about the sleeve having the longitudinal slot therein so thatif the pin passing through the slot approaches either end of the grooveit can displace the plate or ring.

Accordingly, the present invention has for an object to improve theconstruction of the means so as to render the same more economical. Aspecific object, therefore, is to provide in a pencil of this charactera structure in which a spring pressed ring is disposed to normally closethe groove at one end of the casing while the longitudinally movablepencil tip normally closes the opposite end of the groove in the casing.

A further and more specific object is to provide in a structure of thischaracter a single spring which acts simultaneously on the pencil tipand the ring to normally close both ends of the groove in the casing,

According to the invention, a spring means is provided only at one endof and around the outer sleeve that has the longitudinal slot thereinand which spring presses against a loose plate or ring bearing upon theadjacent end of the helicoidal groove in the easing wall and alsoagainst a plate or ring secured at the end of the longitudinally slottedouter sleeve remote from the pencil tip, while the other end of theouter sleeve is secured to the tip of the pencil which bears upon theother end of the helicoidal groove.

The invention will now be described with ref erence to the accompanyingdrawing which shows a longitudinal section through a pencil embodyingthe invention.

As shown in the drawings, the pencil includes a casing 8 having ahelicoidal groove l on the inner wall thereof. Within the casing asleeve 3 extends and which sleeve is provided with a longitudinal slot4, the sleeve 3 being secured to the tip l2 of the pencil, the tiphaving a bore therein through which the lead passes. Within the sleeve 3is disposed a longitudinally movable inner sleeve I and protruding fromthis sleeve is a pin 5 having a guide member 6 on the outer end thereofand which pin passes through the slot 4 of the outer sleeve so that theguide member is disposed within the helicoidal groove i in the casingwall. The arrangement is such that upon rotation of the pencil tip thepin and slot connece tion between the inner and outer sleeves and thedisposition of the guide member Within the groove l eiiects displacementof the inner sleeve 2 and the lead with respect to the outer sleeve andthe casing.

As indicated in the drawing the inner end of the tip bears against theinner or bottom end of the casing when the pencil is held vertically andthe tip further includes a portion which bears against one end of thegroove 1. Bearing against the open end of the groove 'l is a loose ring9 and in longitudinally spaced relation with respect to the ring 9 is aring IU which is secured to the outer sleeve 3. Between the rings springmeans Il, preferably a spiral or coil spring, is disposed and whichspring means urges the rings 9 and l 0 in opposite directions. Since thering 9 is bearing against the end of the groove the action of the springin bearing against the ring lil normally urges the tip I2 into abuttingrelation with the outer or bottom end of the casing. By the same tokenthe resiliency of the spring means permits outward movement of the tipl2 with respect to the casing 8.

The arrangement is such that upon rotating 3 will effect displacement ofthe ring 9 against the action of the spring I l so that the guide memberand pin rotate freely outside the end of the groove 1. On reverserotation when the guide member is moving in the groove 1 toward the tip,the guide member on reaching the lower end of the groove will displacethe tip which is secured to the outer sleeve 3 against the action of thespring I l so that the pin and guide member will rotate freely outsidethe lower end of the sleeve.

It is therefore clear that I have provided a mechanical lead pencilincluding a casing 8 having a helicoidal groove 'I on the inner wallthereof, a sleeve 3 having a longitudinal slot 8 therein disposed withinsaid casing, a second lead holding and feeding sleeve I mounted withinsaid iirst sleeve and having a pin 6 thereon passing through the slot inthe first sleeve and cooperating with the helicoidal groove in thecasing. The pencil tip I2 has a central bore therethrough surroundingboth said sleeves and secured to one end of said first sleeve 3 so thatupon rotation of said tip cooperation between said pin and' grooveeffects feeding of the second sleeve longitudinally of the casingdependentl upon the direction of rotation of the tip. One end of saidcasing bears against the nnner end of said tip and said tip has aportion bearing against one end of said groove, the tip beinglongitudinally displaceable relative to said casing. I provide a loosering member 9 within said casing surrounding said first-mentioned sleeveand bearing against the other end of said helicoidal groove, a secondring member I0 within said casing and carried by said first-mentionedsleeve 3 and disposed in longitudinally spaced relation relative to saidfirstmentioned ring member 9 and a spring l l between the ring membersnormally pressing said loose ring against the adjacent end of saidgroove so that upon excessive rotation of said first-mentioned sleeve ineither direction the resilience of the spring and the movability of thetip with respect to the casing permits the pin to escape through theends of the groove and rotate freely outside the respective ends of thegroove.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent is:

A mechanical lead pencil including a casing having a helicoidal grooveon the inner Wall thereof, a sleeve having a longitudinal slot thereindisposed within said casing, a second lead holding and feeding sleevemounted within said rst sleeve and having a pin thereon passing throughthe slot in the rst sleeve and cooperating with the helicoidal groove inthe casing, a pencil tip having a central bore therethrough surroundingboth said sleeves and secured to one end of said first sleeve so thatupon rotation of said tip cooperation between said pin and grooveeffects feeding of the second sleeve longitudinally of the casingdependent upon the direction of rotation of the tip, one end of saidcasing bearing against the inner end of said tip and said tip having aportion bearing against one'end of said groove, said tip beinglongitudinally displaceable relative to said casing, a loose ring memberWithin said casing surrounding said rstmentioned sleeve and bearingagainst the other end of said helicoidal groove, a second ring memberwithin said casing and carried by said firstmentioned sleeve anddisposed in longitudinally spaced relation relative to saidfirst-mentioned ring member, a spring between the ring members normallypressing said loose ring against the adjacent end of said groove so thatupon excessive rotation of said first-mentioned sleeve in eitherdirection the resilience of the spring and the movability of the tipwith respect to the casing permits the pin to escape through the ends ofthe groove and rotate freely outside the respective ends of the groove,

KARL JosEE svENssoN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,546,490 Kahn July 21, 19252,496,554 Lynn Feb. '7, 1950 FOREIGN PATENTS Number Country Date 1,216Great Britain 1865 171,746 Switzerland Apr. 1, 1935

